Re: [CAD_CAM_EDM_DRO] Need a circuit breaker.......

Sizing servomotors for CNC applications can be a bit fraught as they are
often operated on very short accel/run/decel cycles with little run time at
any sort of load. The peak currents during accel and decel are often twice
or more times the rated current.

I would like to know why they are burning out and to do this you will need
to measure the running currents and the duty cycle.

Regards Peter

----- Original Message -----
From: "Mr. sausage" <sirsausage@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Tuesday, March 26, 2002 3:02 PM
Subject: Re: [CAD_CAM_EDM_DRO] Need a circuit breaker.......


> The question I have is: Why are these motors "burning out"? Are they not
> properly sized for the job? Unless they are seeing fault conditions
> (hitting stops, brakes on etc) they shouldn't normally be overloaded to
the
> point of destruction.
>
> Thermal overloads, circuit breakers etc. cures the symptom, not the
problem.
>
>
> >From: "Peter Seddon" <peter@...>
> >Reply-To: CAD_CAM_EDM_DRO@yahoogroups.com
> >To: <CAD_CAM_EDM_DRO@yahoogroups.com>
> >Subject: Re: [CAD_CAM_EDM_DRO] Need a circuit breaker.......
> >Date: Tue, 26 Mar 2002 09:07:49 -0000
> >
> >Is that the best way to protect motors from burning out? A 7Amp slow blow
> >fuse will carry 7Amps minimum for ever which is above your motor rating.
> >Fuses and circuit breakers are really designed for short circuit
protection
> >and not thermal protection.
> >
> >The best way to protect a motor is by embedded thermal detectors which
> >detect the actual motor winding temperature but are installed when the
> >motor
> >is built and best suit ac motors which have stationary windings. The
> >alternative is a thermal overload relay in series with the motor but this
> >often trips too early as it does not have the thermal inertia of the
motor.
> >
> >I would try a thermal overload relay and leave fuses and circuit breakers
> >for short circuit protection.
> >
> >Regards Peter
> >
> >
> >----- Original Message -----
> >From: "doug98105" <dougrasmussen@...>
> >To: <CAD_CAM_EDM_DRO@yahoogroups.com>
> >Sent: Monday, March 25, 2002 11:16 PM
> >Subject: [CAD_CAM_EDM_DRO] Need a circuit breaker.......
> >
> >
> > > Group,
> > >
> > > It's recommended by the maker of the DC servos on my lathe that I
> > > install a 7 amp slow blow fuse or circuit breaker to protect the
> > > motors (2 motors burned up in last 4 years, $820/each).
> > >
> > > Motors are rated 4.6 amp continuous, 18.4 peak. Max volts 100.
> > >
> > > The motor manufacturer offers a breaker protected motor, but it won't
> > > fit in my space with the breaker protruding from the side. Their
> > > circuit breaker reset is sided mounted with protective cover, .63"
> > > square by .813" tall (fairly small considering that includes the
> > > cover). They buy the breaker from Newark, no part number is
> > > available to me, though.
> > >
> > > Anyone have suggestions, brands, etc. I can't seem to come up with
> > > much locally. What I find here are rated 32VDC, would that be okay?
> > >
> > > thanks,
> > >
> > > Doug
> > >
> > >
> > > Addresses:
> > > FAQ: http://www.ktmarketing.com/faq.html
> > > FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> > >
> > > OFF Topic POSTS: General Machining
> > > If you wish to post on unlimited OT subjects goto:
> >aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it
if
> >you have trouble.
> > > http://www.metalworking.com/news_servers.html
> > >
> > > http://groups.yahoo.com/group/jobshophomeshop I consider this as a
> >sister site to the CCED group, as many of the same memembers are there,
for
> >OT subjects, that are not allowed on the CCED list.
> > >
> > >
> > >
> > > Post messages: CAD_CAM_EDM_DRO@yahoogroups.com
> > > Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
> > > Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
> > > List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com, wanliker@...
> > > Moderator: jmelson@... timg@... [Moderator]
> > > URL to this page: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
> > > bill,
> > > List Mom
> > > List Owner
> > >
> > >
> > >
> > > Your use of Yahoo! Groups is subject to
> >http://docs.yahoo.com/info/terms/
> > >
> > >
> > >
> > >
> >
> >
> >Addresses:
> >FAQ: http://www.ktmarketing.com/faq.html
> >FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> >
> >OFF Topic POSTS: General Machining
> >If you wish to post on unlimited OT subjects goto:
> >aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it
if
> >you have trouble.
> >http://www.metalworking.com/news_servers.html
> >
> >http://groups.yahoo.com/group/jobshophomeshop I consider this as a
sister
> >site to the CCED group, as many of the same memembers are there, for OT
> >subjects, that are not allowed on the CCED list.
> >
> >
> >
> >Post messages: CAD_CAM_EDM_DRO@yahoogroups.com
> >Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
> >Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
> >List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com, wanliker@...
> >Moderator: jmelson@... timg@... [Moderator]
> >URL to this page: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
> >bill,
> >List Mom
> >List Owner
> >
> >
> >
> >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
> >
> >
>
>
>
>
> _________________________________________________________________
> Send and receive Hotmail on your mobile device: http://mobile.msn.com
>
>
> Addresses:
> FAQ: http://www.ktmarketing.com/faq.html
> FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
>
> OFF Topic POSTS: General Machining
> If you wish to post on unlimited OT subjects goto:
aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if
you have trouble.
> http://www.metalworking.com/news_servers.html
>
> http://groups.yahoo.com/group/jobshophomeshop I consider this as a
sister site to the CCED group, as many of the same memembers are there, for
OT subjects, that are not allowed on the CCED list.
>
>
>
> Post messages: CAD_CAM_EDM_DRO@yahoogroups.com
> Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
> Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
> List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com, wanliker@...
> Moderator: jmelson@... timg@... [Moderator]
> URL to this page: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
> bill,
> List Mom
> List Owner
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
>